Color improvement of cottonseed oil



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nited States Patent COLOR HVIPROVEMENT 0F COTTONSEED OIL Frank A. Norris, La Grange Highlands, 111., assignor to iiivifh & Company, Chicago, Ill., a corporation of mols No Drawing. Application April 25, 1957 Serial No. 654,980

Claims. (Cl. 260-423) The present invention relates to a process for improving the color of cottonseed oil. More particularly, this invention is directed to a method of treating crude cottonseed oil to improve the refined color of the oil.

Crude cottonseed oil has a dark, reddish brown color due to the presence of pigmented materials such as gossypol, carotinoids, chloriphyll and various resins. The quality of a particular batch of oil is determined by its crude color and by the color of the oil after refining. The color of crude oil varies according to the amount 2f rainfall and the geographic location of the cotton elds.

Under ordinary conditions, alkali refining of cottonseed oil removes a suflicient amount of color impurities from the oil to provide a product meeting prevailing color standards. Where the crude oil is unusually dark due to weather or other conditions, however, the refining step often has to be repeated in order to lighten the oil to an acceptable color. This second refining step entails considerable expense and, therefore, is undesirable from an economic standpoint.

Crude cottonseed oil contains a number of minor constituents or gums which separate from the oil under certain conditions. Inasmuch as the crude oil containing gums is more valuable than the degummed product, it is important from an economic standpoint to retain these materials in the oil.

It is an object of the present invention, therefore, to provide a method of treating crude cottonseed oil to improve the color of the refined product.

Another object of the invention is to provide a method of improving the color of refined cottonseed oil, which method does not cause the gums to settle out from the crude oil.

Other objects not specifically set forth will become readily apparent to one skilled in the art from the following detailed description of the invention.

In general, the present method consists of mixing crude cottonseed oil with hydrogen peroxide under controlled conditions prior to the refining step.

' Although oxidizing agents have been used to lighten the color of refined oils for many years, they have been considered to have a detrimental efiect on crude oils and on edible oils. Cottonseed oil in particular has been said to darken upon oxidation because of the development of new pigments from this action. In addition, it was felt that oxidizing agents should not be used on edible oils because of their tendency to destroy antioxidants in the oil, thereby producing an unstable product.

Contrary to the above, it has been found that if crude cottonseed oil is mixed with at least 0.05% hydrogen peroxide in the absence of more than from about 0.25 to about 0.35% moisture and volatile materials, that a substantial improvement in the color of the oil can be produced on refining over untreated, refined oils without decreasing the stability of the product.

The following examples illustrate the use of the present "ice invention in improving the color of refined cottonseed oil.

Example I FFA Refined Bleach color color Untreated 3.9 18 2 10.0 Treated 4.3 7 8 6.2

Example II A second batch of crude cottonseed oil was treated in the same manner as is described in Example I. A comparison of the refined and bleached oil with an untreated refined and bleached sample from the same batch gave the following data:

FFA Refined Bleach color color Untreated 1. 0 4. 9 l. 7 Treated 1. 3 4. 0 1. 2

Example III Color determinations were made of several samples of refined and bleached cottonseed oil to determine the effect of treating the crude oil with various amounts of hydrogen peroxide. In each case, a 50% H 0 solution was mixed with the oil and the product-was heated under vacuum to reduce the moisture and volatile materials content of the oil to less than 0.3 percent.

Amount hydrogen peroxide used, percent Refilned co or Amount hydrogen peroxide used, percent Refined Bleached color color Example IV Several quantities of crude cottonseed oil from a common source were mixed with 0.25% H 0 at various temperatures. The samples were heated under vacuum to reduce their moisture and volatile materials content to about 0.25% and then were refined. The results of color determinations of the refined products were as follows:

Example V In order to determine whether the H treatment caused a color reversion after refining and bleaching, samples treated as shown in Example I were compared with untreated samplesfollowing various storage periods.

The above results show that the treatment actually improved color reversion tendencies.

Examples VI The following tests were made to determine what effect insufficient mixing of crude cottonseed oil and hydrogen peroxide might have on the color improving action of the H 0 Treatment FFA Refined Color Control 1. 9 17. 3 Oil+0.25% HzO2+slight stirring 2.0 10.8 01l+0.25% H1Og+rapid stirring 2.0 7 3 From the above data, it is evident that rapid and thorough stirring increases the efiiciency of the present method.

Example VII Inasmuch as hydrogen peroxide treated cottonseed oil would likely be stored. in black iron tanks, a test was run to d'etermine'whether the particles of iron associated with the tanks would decompose the peroxide. The results below indicate that the iron did not affect the bleaching action of the peroxide.

Treatment FFA Refined Color Control 1.9 17.3 Oil+0.25% H0,+.01% Fe O -l-rapid stirring 2.1 7. 4

One of the important steps of the present method lies instripping the moisture and volatile materials contained in'theoil'down to a level where gums contained in the crude product will not settle out. Crude cottonseed oil containing phosphatides is considerably more valuable than the oil and separated phosphatides. For this reason, it is important that any color improving process be capable of lightening the color of the product without causing degumming.

It has been found that if no more than about 0.25% moisture and volatile materials is present, that a substantial improvement in. the color of the cottonseed oil will be noted on refining without causing the loss of gums from the crude oil'. Certain crude cottonseed oils will not degum until their moisture and volatile materials content goes above 0.35%.

Example VIII The following chart shows certain temperature and vacuum conditions which produce a satisfactory moisture and volatile materials content:

Vacuum Moisture Temperature in C. in In. of and Vola- Mercury tile Matter The reaction time needed to treat crude oil pigments so that they can be readily removed'on refining will not usually exceed a few minutes. Under ordinary processing conditions, however, the oil often is not refined for several days after the hydrogen peroxide treatment.

It has been observed that oils high in free fatty acids (above about 10%) are not as much improved by the subject method as are oils. having low percentages of free fatty acids. An oil sample containing 10.4% free fatty acids, for example, showed acolor improvement on refining of from about 106R to 9.6R when treated with 0.25% hydrogen peroxide. A similar sample having a 4.3% free fatty acid content was lowered to 8.75R under the same conditions.

Inasmuch as the oil is stripped of excess moisture in order to prevent degumming, the H 0 can be added at any desired solution concentration. It is important, however, that at least about 0.05 of H 0 be mixed with the crude oil.

The descnibed process of treating crude cottonseed oil with H 0 produces a wholesome, edible oil, free from any traces of chemicals added for decolorizing purposes. The oil does not suffer any decrease in stability against rancidity from the action of hydrogen peroxide but merely is improved in color. Because the oil is stripped of excess moisture, phosphatidic materials do not become hydrated and settle out of the oil. Any such separation would cause storage problems and would result in the production of crude cottonseed lecithin which has no substantial commercial value to date.

Obviously many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A method of treating cottonseed oil which comprises: adding to crude cottonseed oit at least about 0.05% by weight of hydrogen peroxide; and reducing the moisture content of the oil to less than about 0.35% by means of heat and vacuum prior to separation of the gums from the oil.

2. A method of improving the color of cottonseed oil which comprises: adding to crude cottonseed oil at least about 0.05 by weight of hydrogen peroxide; reducing the moisture content of the oil to' less than. about 0.35% before the gums settle out of the oil; and thereafter refining said oil.

3. A method of improving the color of cottonseed oil without causing degumming, which comprises: adding to crude cottonseed oil atv least about 0.25% by weight of hydrogen peroxide; reducing themoisture content of the oil to less than about 0.35% by means of heat and vacuum; and thereafter refining said oil.

4. A method of improving the color of cottonseed oil without causing degumming which comprises: adding to crude cottonseed oil at least about 0.25% by weight .of hydrogen peroxide; reducing the moisture content of 5 the oil to less than about 0.25% by means of heat and vacuum; and thereafter refining said oil.

5. The method of treating crude cottonseed oil pigments so that they can be readily removed upon subsequent refining, which comprises adding at least about 0.05% by Weight of hydrogen peroxide to crude cottonseed oil containing said pigments and reducing the moisture content of the oil to less than about 0.35% whereby gums contained in said oil will not settle out.

References Cited in the file of this patent Mattikow Oct. 10, 1950 FOREIGN PATENTS Great Britain Sept. 10, 1925 

1. A METHOD OF TREATING COTTONSEED OIL WHICH COMPRISES: ADDING TO CRUDE COTTONSEED OIL AT LEAST ABOUT 0.05% BY WEIGHT OF HYDROGEN PEROXIDE: AND REDUCING THE MOISTURE CONTENT OF THE OIL TO LESS THAN ABOUT 0.35% BY MEANS OF HEAT AND VACUUM PRIOR TO SEPARATION OF THE GUMS FROM THE OIL. 